1. Technical Field
This invention relates generally to methods, systems and apparatus for managing digital data transmission and/or communications systems.
2. Description of Related Art
Digital subscriber line (DSL) technologies can provide large bandwidth for digital communication over existing telephone subscriber lines (also referred to as loops and/or the copper plant) and can adjust to the characteristics of a line by using discrete multitone (DMT) line code that assigns a number of bits to each tone (or sub-carrier), adjustable to channel conditions determined during training and initialization (typically by transceivers that are both transmitters and receivers) at each end of the subscriber line.
In DSL communications systems, significant performance gains can be achieved by reducing the crosstalk that occurs among the twisted pairs, as is well known by those skilled in the art. One such technique for reducing crosstalk is to suppress the far-end crosstalk by jointly processing the signals transmitted and/or received by a group of lines, commonly referred to and described as “vectoring.” When vectoring is applied to improve performance in the downstream transmission direction among a group of lines that do not have a common termination point, then joint signal processing can only take place at the transmitter side. This joint signal processing is often described as preceding.
Systems, apparatus, methods and techniques that improve precoding would represent a significant advancement in the art. More specifically, systems, apparatus, methods and techniques for implementing such precoding that are implementation adaptive to changes in the channel and noise, permit dynamic subtraction based on power limitation and utilize modulo operation and dither signal likewise would represent a significant advancement in the art.